Five U.S. citizens were on their way from Tehran to Qatar as part of a prisoner exchange between Tehran and Washington, a high-ranking U.S. official said on Monday.
Two family members were also on the plane, the official said.
It has been known for several weeks that the U.S. and Iran were negotiating a prisoner exchange.
In August, Iran’s judiciary released several U.S. citizens from detention and transferred them to house arrest in apparent preparation for the swap.
One of the best known is the businessman Siamak Namazi, who holds both U.S. and Iranian citizenship.
He was imprisoned in 2015 and sentenced to 10 years for espionage.
On the U.S. side, in return, five Iranians who were convicted or charged with non-violent crimes were being granted clemency.
As part of the deal, Iran had demanded the release of about 6 billion dollars in funds that were frozen in South Korea because of international sanctions.
Iran’s Foreign Ministry said on Monday that the funds had arrived in Qatar.